There are a number of situations in which it is important that a door be held releasably but tightly closed against a door jamb. Such a situation is exemplified by large walk-in refrigerators in which case a poor seal between the door and the door jamb can result in substantial transfer of heat through the joint as well as in formation of ice which may interfere with opening and closing of the door. A further problem arises from the fact that individuals entering and leaving the refrigerator may be carrying loads of such weight and size that both hands of the individual are occupied, making it impossible to operate a latch manually.
A variety of devices have been devised for holding such doors firmly closed, but these have been less than completely satisfactory. These devices generally have a bistable feature in that the element responsible for holding the door closed can be moved between an engaged position and a standby position. However, such devices have not been able to provide the required reliability, long life and substantial closing force necessary where the door is large in size. In addition, such devices have not been adaptable to operation from an external signal. Such a signal can be provided by stepping on a mat, intercepting a light beam or pressing on a plate with a knee, for instance. It should be noted that the device need not open the door completely; it is only necessary that the door be opened sufficiently so that a foot can be inserted between the door and the door jamb, such a movement being sufficient for the individual to manage to open the door completely without use of the hands. As is evident, then, it would be desirable to provide a device which can hold a door closed firmly against a door jamb and which provides for either manual or electrical operation in opening the door.